The Study On Operational Efficiency And Technical Design Of A Sewage Treatment Plant

The combined processes of aerated grit chamber, hydrolysis acidification tank,anoxic tank, garrousel oxidation ditch, coagulation and sedimentation tank in thesecond wastewater treatment plant in Yishui County were taked as the object of theresearch. We systematically investigated the function and parameter of every structurefor the the combined processes in the wastewater treatment plant, and evaluated theperformance of combined processes. We analyzed the microbial morphologicalcharacteristics and community structure for the hydrolysis acidification tank, anoxictank and garrousel oxidation ditch.The concentrations of effluent COD, BOD₅, TN, NH₄⁺-N, TP, SS were below47,7.8,11.4,2.8,0.5and7.8mg/L, respectively, which did not exceed the limit values ofthe discharge standard of pollutants for municipal wastewater treatment plant. Wheninfluent concentrations of pollutant were below the design values, the effluentconcentrations of pollutant were not affected by the increment of water quantity. Theeffect of seasonal changes on the performance of combined processes was notsignificant. However, the effect of seasonal changes on the sludge settleability wassignificant. The sludge settleability was poor, when the ambient temperaturte was low.The SVI values varied within the range between22and33mg/L in spring andsummer, however the SVI values varied within the range between28and47mg/L inautumn and winter. The reduction of COD, BOD₅, TN, NH₄⁺-N, TP and SS were4340,1184,1159,255,258and24t, respectively.Observe microbial forms with scanning electron microscope, the results showedthat bacilli and cocci were the major species in the hydrolysis acidification tank andanoxic tank. Bacilli and cocci were always observed in different part of oxidationditch, however filamentous bacteria were only observed in the middle part ofoxidation ditch. In the hydrolysis acidification tank, Ruminofilibacter xylanolyticum、Brachymonas denitrificans、Dysgonomonas mossii and Brooklawnia cerclae weredominant strains. In the anoxic tank, filamentous bacterium Plant1Iso8、 Ruminofilibacter xylanolyticum、Dysgonomonas mossii、Dechloromonas sp. JJ、Nitrospira sp. and bacterium Ellin6519were dominant strains. In the front ofgarrousel oxidation ditch, filamentous bacterium Plant1Iso8， Ruminofilibacterxylanolyticum，Brachymonas denitrificans，Dechloromonas sp. JJ，Nitrospira sp，bacterium Ellin6519were dominant strains, however Dechloromonas sp. JJ andbacterium Ellin6519disappear in the end of oxidation ditch. filamentous bacteriumPlant1Iso8， Ruminofilibacter xylanolyticum， Brachymonas denitrificans，Dysgonomonas mossii，Brooklawnia cerclae were always the superior strains in thedifferent part of oxidation ditch.